What to do if the microwave works but does not heat

Sometimes, putting food to reheat / defrost, we are surprised to find out that the microwave does not heat. Everything works, glowing, spinning, but the food remains cold. What to do? In order not to carry it for repairs, you can try to fix the damage yourself.

Why problems can arise

As usual, the reasons for the breakdown of a microwave oven lie in non-observance of the rules of operation. This accounts for most of the problems with household appliances and this case is no exception. Most often, problems begin after:

• There is a metal object in the cooking space during heating / defrosting / cooking. Most often, this is a spoon or fork that is in the container with food. At the same time, the microwave begins to spark, and then it starts to be capricious - it sparks, does not heat food.
• Another fairly common situation that often leads to breakdowns is heating in a sealed container that is not intended for this. When a certain temperature is reached, the dishes explode, the food scatters around the chamber, clogging the oven parts. It is rare that such an incident remains without consequences (washing the chamber does not count).
  

  The location of the parts can be like this

• Also, users often forget that they cannot turn on the microwave oven when empty. In this mode, it starts to spark even more than if there is a metal object in it. The result is problems with the magnetron and the microwave does not heat.

Cheap stoves can often break down. They are made in such a way that they are less repaired and more often bought new. And the last obvious reason is the wear of the parts. If your oven has been in service for a decent number of years, most likely the parts have simply exhausted their working life. As you can see, there are not many technical reasons. Basically, these are erroneous actions of "users". The result is that the microwave does not heat up or does not turn on at all.

Microwave device

To make it easier to repair a microwave oven, let's get acquainted at least in general terms with its device. Most of all we are interested in her "insides".

Microwave device

Generates microwaves magnetron. It is connected to the camera by a rectangular waveguide. In some models, the waveguide is covered by a piece of mica (a gray-brown material that looks like metal), in others, a plastic cover. The magnetron is powered by a transformer, capacitor and diode. There is often a high voltage fuse in the power circuit to protect the transformer from overload.

There is a fan for cooling the magnetron. Warm air from the magnetron also enters the working chamber through the air duct, which accelerates the heating of food. Steam and excess air are removed from the chamber through special openings that do not allow radiation to pass through.

If the microwave does not heat, you will have to repair it

All other reasons are more serious and must be dealt with separately.

More serious reasons

In this section, we will consider the damage that can lead to the fact that the microwave does not heat, although everything is spinning / glowing. To restore performance is more difficult than in the previous paragraph, but not so much that it was impossible to do it yourself.

Approximate arrangement of parts in a microwave oven

Fuse

Sometimes the microwave does not heat up due to a faulty fuse in the magnetron power circuit. It is not present in all models, but it can cause the magnetron to not work. This fuse is sometimes installed openly, but most often in a protective casing (see not the photo), since it stands in a high-voltage circuit.

High-voltage fuses in microwave ovens can be placed in a protective cover

It consists of a glass flask with metal caps installed at the edges. There is a spring-loaded wire inside, soldered from one end to the contact of the cap. Unlike conventional fuses, this does not blow the wire. With prolonged operation, the solder heats up and softens, the spring force spreads the contacts.

High voltage fuse structure

If the fuse does not ring and an open circuit is visually visible, there are two ways to solve the problem - replace it or restore the soldering. To restore the high-voltage fuse, you must carefully remove the metal cap on the side from which the wire was soldered off, solder it into place. Return the cap to its place and check if it is heating up or not.

Magnetron problems

There are several damages associated with the magnetron. Let's start again with the simplest - weak contacts. The wires from the filament winding of the transformer come to the terminals (to the connector) of the magnetron. They should be difficult to remove. The contact may have deteriorated from heat. It can be improved by additionally crimping the contacts with pliers.

Magnetron device

Sometimes the microwave does not heat up due to damage to the magnetron antenna cap. If the cap is simply blackened or there is a solidified drop of metal on it, but there are no extra holes, it is necessary to clean everything to pure metal, make the surface even. You need to work with fine sandpaper. We achieve the maximum effect - everything should be even / smooth, preferably to a mirror shine. But don't rub the metal to the holes. At the end of the work, carefully remove all the dust. The best way to do this is a vacuum cleaner.

Antenna cap is damaged

If the cap is melted - as in the photo above, you need to make sure that the magnetron itself is not damaged and there is a vacuum in the middle. To do this, carefully remove the cap and inspect what is under it. If the metal is intact, you can simply replace the cap. If not, you will have to change the magnetron, but at the same time you need to think about the advisability of such a repair - the price of this spare part is high, maybe you just need to buy a new furnace.

How to replace the magnetron cap? It is very difficult to find it on sale - it costs a penny, selling it is unprofitable. There is an option - to grind on a lathe. If this method does not suit you, you can make a suitable size from an old electrolytic capacitor.

Old damaged cap and a new one from the capacitor

We select an element of a suitable diameter, cut off the desired piece of the body, carefully drill a hole in the center. All measurements must be perfect. After that, we clean the body with the finest sandpaper and polish: the quality of the microwave depends on the conductivity of the cap. We put the finished cap in place, check the work.

If you still decide to replace the magnetron, then take it with you to the store. The new one must match in terms of output power, the antenna must be the same length, and the mounting lugs must also be located in the same place and on the same side. Only then can it be installed in place of the old one.

Mica plate problems

From the side of the chamber, the exit of the waveguide is covered with a plate of mica. Sometimes the microwave does not heat up due to the fact that carbon deposits have formed in it and the waves simply cannot overcome this obstacle.Also, due to such damage during operation, sparks and something similar to lightning or even fire may appear.

Darkening is visible on the mica plate

In this case, remove the plate by unscrewing the screws (from two to eight pieces). If there are no irreparable changes (no hole), you can try to clean up the blackened place. We take fine sandpaper and carefully clean everything off. We carefully remove the dust (you can use a vacuum cleaner), put the plate in place. To be sure everything works, you can turn it upside down.

If there is a hole in the plate, it is best to replace it. This spare part is on sale, in stores they know about microwave mica. Put the new plate in place (you may need to drill holes for fasteners) and check. If the microwave does not heat the food because of this, everything should work.

Burnt capacitor or faulty diode

If the microwave stops heating, everything turns on, buzzes, spins, but the food remains cold, perhaps it's the condenser. We take a tester and check it. We set it to the resistance measurement mode.

Microwave condenser

If during measurement it shows an open circuit - it is inoperative, if it shows a small resistance - it is also under replacement, since it is broken. Only if, when touching the capacitor, the arrow "flies away" to infinity - it is in a normal state.

Checking a high-voltage diode is not an easy task, therefore most often it is simply replaced. It doesn't cost enough to be a problem. Naturally, the parameters of the new part must match.

There can be many more reasons that the microwave does not heat up - it is necessary to consistently check all the elements and conductors. But since the manufacturers' schemes are different, you need to figure it out on the spot. In principle, in the process of finding out all the breakdowns described above, you will see if the wire is soldered / frayed, the soldering has moved away, etc. You monitor and eliminate all these nuances. In theory, it should earn.